Does Water Fluoridation Cause Cancer?

Since the inception of water fluoridation, there have been unsubstantiated claims that water fluoridation causes a variety of health problems – cancer, Down Syndrome, Alzheimer’s, bone disease, kidney problems, allergic reactions, etc. To ensure the public that these claims are false, many organization have moved, one by one, to endorse water fluoridation – the National Cancer Institute & the American Cancer Society; Down Syndrome Society; Alzheimer’s Association; American Osteopathic Association; National Kidney Foundation; Academy of Allergy, Asthma, and Immunology, and many others.

Harvard Study

In 2006, the claim that fluoridation causes cancer resurfaced, citing preliminary reports from a Harvard study. The Harvard study is a 15-year study looking at a possible link between osteosarcoma (a rare type of bone cancer) and water fluoridation. The data was collected from 1989 to 2004. The research director, Dr. Chester Douglas, was accused by those opposed to fluoridation of suppressing a paper written about the studies preliminary results. An ethics violation was filed with both Harvard and the National Institute of Health who is funding the study. Dr. Douglas was cleared by both institutions of any ethics violations.

Dr. Elise Bassin’s thesis, published in 2000, was based on data collected from the first 3 years of the study (1989-1992). Dr. Bassin reported an age-specific increase in cancer rates in young males but not among young females. The author clarified that there “are several limitations to our study. She stated that “the etiology of osteosarcoma is not known,” that “fluoride may not be the causative agent,” and that there were as of yet [no bone biopsies to analyze fluoride content.]

NOTE: One of the requirements of sound research is that the results be reproducible.

The second set of cases analyzed (1993-2000) do not replicate the overall findings from the Bassin thesis. This second part of the study also includes extensive analysis of bone specimens, comparing cancerous and non-cancerous lesions for fluoride content. Dr. Douglas reports, “Our findings currently being prepared for publication, do not suggest an overall association between fluoride and osteosarcoma. Our preliminary analysis of the fluoride content of the bone specimens suggests that the fluoride level within the bone is not associated with excess risk of osteosarcoma. We are grateful to Dr. Bassin and her coauthors for mentioning at the end of their paper that we are not finding a positive association from the bone specimens in the second set of cases.” Article by Dr. Douglas

In 2000, the National Institute of Environmental Health Sciences (NIEHS), one of the sponsors of the Harvard study, widely disseminated in the results of a first study (1990) that indicated a link with osteosarcoma and fluoride in male rats when the animals were dosed with concentrations of 25, 75, and 100 times the amount of fluoride found in optimally fluoridated water. A second NIEHS study, however, did not replicate the results of their first study. Drinking water with very high fluoride content was not found to be associated with osteosarcoma in either male or female rats.